There are known an image forming apparatus that performs image formation using a decolorizable toner and an erasing device that changes an image from a color developed state to a decolored state. The decolorizable toner used in such an image forming apparatus is decolorized when a color former compound and a color developer are disconnected by heat.
The erasing device is provided separately from the image forming apparatus. However, there is known a fixing device in the image forming apparatus also used as the erasing device taking into account space saving. In general, temperature necessary for decolorizing a toner is higher than temperature necessary for fixing the toner. Therefore, the fixing device also functioning as the erasing device operates as the erasing device by raising the temperature of the fixing device when the fixing device is about to perform an erasing operation.
However, if the temperature of the fixing device is once raised, since the fixing device is formed of a material having high heat accumulation properties such as rubber, it takes time to lower the temperature to the temperature suitable for fixing again. On the other hand, if the fixing is performed in a state in which the temperature does not sufficiently drop, excessive melting of the toner called high-temperature offset occurs. Therefore, even if a user attempts to perform copying or the like while a erasing operation is performed, the user has to wait until the temperature of the fixing device drops, leading to poor operability.